Legally hand over classic horror story penned by West Country runner (9)
I believe the answer is:
extradite
'legally hand over' is the definition.
'classic horror story penned by west country runner' is the wordplay.
'classic' becomes 'trad' (abbreviation of traditional).
'horror story' becomes 'it' (Stephen King novel).
'penned by' indicates putting letters inside.
'west country runner' becomes 'exe' (river of Devon and Somerset).
'trad'+'it'='tradit'
'tradit' inserted into 'exe' is 'EXTRADITE'.
(Other definitions for extradite that I've seen before include "Hand over to a foreign government for trial" , "Hand over for trial to another government" , "Hand over (felon) to another country" , "Bring from abroad" , "Hand over to a foreign jurisdiction" .)